Copenhagen



Aug. 2s, 192s. 1,682,303

s. MHL

HYDRAULIC CHANGE SPEED GEARING Filed March :51. 1922 Patented Aug. 28, 1928.

UNITED STATES PATENT oFElcE.

srm'rmt Kln., or cormnamr, immun.;

HYDRAULIC CHANGE-SPEED GEARING.

`Application led March 31, 1922, Serial lo. 548,553, and in Denmark April 9, 1921.

The present invention relates to a. hydraulic change-speed and reversing aring device with pump and motor of varia le productivity both constructed according to the ear-pum system of the type described in atent o. 1,603,395 granted to me under date of October 19, 1926. The distinguishing feature of the invention is that said pump and motor each comprises a pair of intermeshing ears, one of said gears forming an internal y toothed drum disposed in concentric relation to the shaft and the other an externally toothed gear journalled about an eccentric disc, one of said eccentric discs being fixed on the driven shaft, while the other eccentric disc is mounted for limited rotative movement about this shaft. Between the um and motor, and similarly mounted fIdr limited rotative movement about the driven shaft, is disposed a member in tight-fitting enga ement with both, said member being providged with a communicating channel, the organization being such that when said disc is rotated about the shaft the meshing fields of the two airs of gears are displaced relatively to t e position of the connecting channel whereby .the ratio of gearing may be changed or rection of rotation reversed.

Another distinguishing feature of the in- L vention is that one of the internally toothed drums is rigidly conected tothe ear casing, in such a manner that the casing itself will be rotatable. A

In the drawings accompanying and forming part of this specification,

Fig. 1 is a longitudinal section showin by way of example a hydraulic change-speed and reversing gearing device embodying the present invention;

l Figs. 2, 3 and 4 are cross-sections taken res ectivel along the lines II--II, III-III an IV- of Fig. 1; and

Fig. 5 a detail.

In the construction shown, M indicates the drivin and L vthe driven shaft, said shafts being dis osed in axial alinement. The gear box G Ig J is rigidly connected to the drivin shaft M and forms bearings for the dr1ven shaft In order to support the entire caring device, the gear box should prefere ly be journalled in fixed bearings, such, for instance, as ball-bearings K, as

the di- W shown in the drawing. Inside of the gear box, which is supposed to be filled with oil or other fluid, there is mounted at one end and close to the end wall G, an internally toothed drum R1, said drum being keyed to the drum H as shown clearly in Fig. 2. An externally toother drum r1, journalled about an eccentric E1 fixed on the driven shaft and resting against the end wall G of the gear box, is in enga ement at one portion of its periphery wit the drum R1.

A similar set of toothed drums R, and r, is provided at the opposite end of the gear box. The drum R2, however, is not rigldly connected to the gear box, but is Ina-de integral with a circular disc P, which is provided with a tubular extension or sleeve N which encircles the driven shaft L and passes through the head J of the gear box, said sleeve carrying outside of the gear box, a brake disc adapted to be acted upon by a brake band b. The eccentric E2, about which the drum r2 is journalled, is not attached to the driven shaft L proper, but to a tubular shaft W encircling the driven shaft, said tubular shaft being itself encircled by the sleeve N. The tubular shaft as hereinafter described, is adapted to be given a slight rotation about the shaft ut normally partakes fully and entirely in the rotation of the latter. The two eccentrics E, and E2 are so disposed that the two sets of toothed drums R1 r, and R, 'l'z have their meshing fields located exactly or approximately opposite one another. Mounted on the shaft L within the tubular shaft W is a tubular shaft V, which extends within the gear box to a oint adjacent to the disc E1 and has secured) thereto an arm T carrying an obturating plate U which fits tightly between the two sets of drums R1 r1 and R2 1', and is provided with a channel Q adapted to communicate with the meshing fields of the two sets of drums R, r, and R, r2. The tubular shafts V and W are adapted to be rotated slightly relatively to the shaft L, but normally rotate together with said shaft.

With the meshing fields thus closed on the sides, when the shaft M is driven fromsome suitable source of power, the set of toothed drums R, r, forms a regular gear pump pumping oil through the channel Q into closed toothed-spaces of the set of toothed Ihn drums R2 r2, which are thereby forced to rotate and, thus, to act as a motor. y

Supposing that the driven shaft L is under load, it will be seen that if the braking disc av is released entirely, then the only effect of the rotation of the driving shaft M will be that the braking shaft or sleeve with ,they braking disc a will commence to rotate (running empty), the motor` having then only to overcome the friction of the sleeve N. If, on the other hand, the brake disc a is braked tightly, so that the resistance against rotation of the sleeve N is considerable, the

. .motor action will manifest itself in that the tor, corresponding to w `take up this pressure and Acenter of the meshing fields,

eccentric E2 with the tubular shaft W and, thereby, also the shaft L (the driven shaft) will be rotated, and this rotation will then also be partaken by the eccentric E1, which is fixed on the shaft L and by the tubular shaft V with the obturating plate U, in such a manner that the fields of engagement and the connectin channel Q between the latter will constant y remain in the same relative position.

During these conditions the oil pressure alone in the pum will cause rotation of the shaft L, the sai pressure causing the eccentric disc E1 to yield in the direction of rotation of the toothed drum R1.

As will be understood from the above eX- planation, the brake disc a in connection with the brake band b will form a clutch for coupling and uncou ling the driving moat is known in other gear constructions.

The pressure exerted by the oil in the pump and motor will exert itself on the circular disc P in axial direction. In order to prevent any excessive friction between the said disc P and the end J of the gear box a thrust bearing may suitably be inserted therebetween in the shape of a ball bearing F.

In order that the pump and motor may operate effectively, it is necessary that the communicating channel Q, b way of which the'oil is to be transferred fiiom one to the other, should not be in alinement with the where the depth of meshing would be practically constant during the passage of the teeth past the channel orifice, so that no oil at all would be passed through the channel. However, when the channel Q is displaced somewhat to the side of the said center, out of meshing field of`the pump, the depth of meshing will increase durin such passage of the teeth and consequent y a certain quantity of oil be forced out from each tooth space into the channel Q. The farther the channel is off' center with relation to the meshing field of drums R, r, (althou h it must always be within the limits of t e meshing field), the larger will be the quantity of oil which the pump, for each passage of a tooth across the channel orifice, will drive into the channel. On the other hand, the uantity of oilwhich the pump drives throng the channel Q will be received the easier by the motor the nearer the channel QA is located to the outer limit of the meshing field of the drums R2 r2, and consequently the slower will be the speed of rotation of the motor. At start the channel Q will be opposite the center of the meshing field o the pump and, at the-same time, far to the side of the center of the meshing field of the motor. The pump will then drive no oil at all into the motor, which consequently will remain 'motionless (gear ratio zero), but merely will remain ready' to receive larger quantities of oil. For starting, after the gearing device has been coupled in, the position of the channel Q relatively to the center of the two meshing fields must be altered in such a manner that the channel is removed slightly from the center of the fields of engagement on the pump side while on the motor side it is moved slightl nearer towards the center of the meshing eld. The pum then forces a small quantity of oil throug the channel Q, and such oil is relatively easily discharged by way of the motor, which is thereby rotated, but only relatively slowly (low gear). The more the channel is removed from the center` of the meshing field of the pump, and simultaneously carried nearer to the center of the meshing field of the motor, the larger will be the quantity of oil that is conveyed, and the faster will the motor be driven (higher gear) until the point is reached Where the channel stands opposite the center of the meshing field of the motor and, simultaneously, quite far away from the centre of the meshing field of the pump. The motor will then be unable to receive any oil notwithstanding the attempts of the pump to drive oil by way of the channel Q. The toothed drums 7*, and 1'2 will therefore not rotate relatively to drums R, and R2 respectively, and consequently the driving and the driven shaft will rotate at one and the same speed (gear ratio equal). The pump and motor will then be coupled together by a fluid-lock. If the increase of ear ratio is continued by moving the channel Q beyond the center of the meshing field of the motor and, at the same time, still nearer to the outer limit of the pump meshing field, then, theoretically at least, overgearing will occur, and the driven shaft will rotate at even higher speed than the driving shaft proper.

If from start the channel Q is shifted to the opposite side of the center of the meshing field of the pump, the pump will begin to act as a suction pump instead of a compression pump, and instead of oil being forced from the pum into the motor, it will then be sucked in the opposite direction through the motor; in other words, the gearing device is now adjusted for backgear.

The above mentioned motion of the channel Q relativel to the center of the meshing fields of t e pump and the motor is e uivalentto a rotation of the tubular shafts V1(with arm T) and W (with eccentric disc E2) about the driven shaft L, and is effected by means of the following mechanism (Figs. 1 and 5).

On the driven shaft L and longitudinally movable thereon is mounted a stepped sleeve c provided on its inner surface with three sets of guiding strips d, m and n, the strips d being parallel with the sleeve, while the strips m. and 11, are helical. The strips d are adapted to slide in grooves in the surface of the shaft L, in the surface of the tubular shaft V, and the strips n in grooves on the surface of the tubular shaft W. The strips d are parallel to the axis of the shaft L, while the strips m form a central small angle and the stri s n a sli htly larger angle with said axis. From t is construction it will readily be seen that when the sleeve c is displaced on the shaft L toward the left of Fig. 1, the tubular shafts V and'W will be slightly rotated relatively to the shaft L, and because of the difference between the helical pitch of the strips m and that of the strips n, the tubular shaft W which carries the eccentric disc E2 will be rotated a greater distance than the tubular shaft V, which carries the member U, thus changing the position of the channel Q with relation to the meshing fields of the .drums R1 'l'1 and R2 r2. v The displacement of the sleeve c along the shaft L may be performed by means of a forked lever, not shown in the drawing, engaging an annular groove f on the sleeve c. When adjustment is made for equal gear ratio and at the same time the coupling a b is released, a rigid coupling between the driving and the driven shaft may be provided. A cou ling device of this nature in the shape of a c utch coupling is shown in the drawing. The hubportion G of the gear box fixed to the drivin shaft M carries a coupling ring g a apted to be shifted by means of a forked lever not shown, the said coupling ring being provided with a diametrically disposed transverse bar h for which the walls of the hub-portion are provided with corresponding slots z'. The end of the driven shaft L is journalled in the hub-portion G, and is provided with a kerf k adapted to receive the transverse bar h of the coupling rin When the couplin rin is shifted towars the gear box, the ar hg will enter into the kerf le, and the driving and driven shafts M and L will then be coupled together directly, in such a manner that any relative motion of the parts in the gear box will be the strips m in grooves` precluded. 'The direct coupling-is released when the coupling ring is shifted away from the gear box so as to withdraw the bar entirely from the kerf k.

aving now particularly described and` ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. Hydraulic gearing device, l.comprising a driving shaft, a gear case mounted for rotation with said driving shaft, a driven shaft, a rotary pump, a rotary motor driven by said ump, said pump and motor being each of t e gear wheel type for variable productivityl and each having an outer and an inner member, a member disposed between said pumpand motor and adapted to transfer pressure fluid from the rotary pump to the rotary motor, and means for altering the position 0f one of the members of the rotary pump relatively to the said transferring member, and the position of the latter relativelyto one of the members of the rotary motor.

2.V Hydraulic gearing device, comprising a driving shaft, a gear case mountedv for rotation with said driving shaft, a driven shaft, an eccentric disc carried by said driven shaft, a rotary pump of the gear wheel type having an outer member firmly connected to the gear case and an inner member journalled on said eccentric disc, a tubular shaft disposed in concentric relat-ion with said driven shaft, an eccentric disc carried by said tubular shaft, a rotary motor of the gear wheel type having an outer member normallyaheld stationary and an inner member journalled on said last eccentric disc, a second tubular shaft disposed in concentric relation to said driven shaft, a member secured to said lasttubular shaft and disposed between said pump and motor and adapted to transfer pressure Huid from the pump to the motor, and means for altering the position of the inner member of the motor relatively to the transferring member and the position of the latter relatively to the inner member of the pump.

3. Hydraulic gearing device, comprisin a driving shaft, a ear case mounted for rotation with said riving shaft, a driven shaft, an eccentric disc carried by said driven shaft, a rotary pump of the gear wheel ty e having an outer member firmly connected) to the gear case and an inner member journalled on said eccentric disc, a tubular shaft disposed in concentric relation with said driven shaft, an eccentric disc carried by said tubular shaft, a rotary motor of the gear wheel type having an outer member normally held stationary and an inner member journalled on said last eccentric disc, asecond tubular shaft disposed in concentric relation to said driven shaft, a member secured to said last tubular shaft los and disposed between said pump and motor and adapted to transfer pressure fluid froml e the pump to the motor,

,the position means for altering of the inner member of the motor relatively to the transferring member and the position of the letter relatively to the inner member of thepump, a mechanical coupling dis osed between the gear case and the driven s aft and adapted to couple Leemans the seid shaft to the member of the motor being firmly connected to a, vband brake disposed outside of the gear case and ada ted to hold the said member stationary uring the. operation of the gearing device.

In testimony whereof I have signed my name to this specification.

STEFFEN MHL.

ar case, the outer 10 

